SPACE NEWS: OneWeb Deployment Reaches Halfway Point With Soyuz 2.1b Launch

dWeb.News Article from Daniel Webster dWeb.News

dWeb.News Article from Daniel Webster dWeb.News

The initial deployment of OneWeb’s satellite broadband constellation reached its halfway stage on Thursday with the launch of 36 more spacecraft aboard a Russian Soyuz 2.1b rocket. Liftoff from the Vostochny Cosmodrome in Eastern Russia occurred at 18: 40 local time (09: 40 UTC) on October 14.

Thursday’s launch is the 11th in a series of flights to deploy OneWeb’s initial constellation of 648 satellites. With 322 satellites already in orbit and 36 more on the way with this launch, the completion of this mission means more than half of the initial constellation has been deployed.

OneWeb satellite constellation

Founded by American businessman Greg Wyler in 2012, OneWeb aims to provide high-speed satellite broadband with a large fleet of small satellites in low Earth orbit similar to SpaceX’s Starlink constellation. OneWeb, unlike Starlink, sees business and government users as its primary customers.

Satellite internet service is a way to provide high-speed connectivity in remote areas that are not easily accessible by terrestrial broadband. This includes rural areas where infrastructure may not be available or would be prohibitively expensive to build.

Traditional communications satellites operate in geostationary orbits, high above the Earth’s equator; however, this presents a difficulty for internet providers as the travel time to and from the satellites results in latency, a delay in the round trip time to request and load data – such as a web page – across the network. This problem is reduced by placing satellites in lower orbits, as signals travel less. However, this means that more spacecraft are needed to provide continuous coverage around the globe.

OneWeb’s satellites were developed in cooperation with Airbus Defence and Space, with a manufacturing facility set up close to Cape Canaveral in Florida to produce the hundreds of satellites needed over the lifetime of the constellation.

While the first 648 spacecraft will make up its initial constellation, OneWeb has committed to building at least 900 satellites. These additional units will be used as spares or replacements in the event that any of the existing satellites fail or are no longer operational.

Each OneWeb satellite has a mass of 147 kilograms and an expected design life of at least seven years. The constellation occupies a near-polar orbit with an altitude of 1,200 kilometers at an inclination of 87.4 degrees. Once fully deployed, the constellation will consist of 18 planes, with 36 satellites in each plane.

The first six OneWeb satellites were launched in February 2019 to allow time for on-orbit testing before operational launches commenced. Subsequent missions have carried groups of either 34 or 36 satellites, with the first operational launches taking place in February and March 2020.

After failing to secure enough investment, OneWeb filed for bankruptcy in March 2020, halting launches. The British government purchased the company along with Bharti Enterprises Ltd three months later. OneWeb was able to exit bankruptcy in November. Launches resumed the next month.

Visualization of a OneWeb satellite in orbit. (Credit: OneWeb)

OneWeb is currently expecting to begin offering an initial commercial service in the Northern hemisphere by the end of the year.

Soyuz Launch from Vostochny

OneWeb selected European launch provider Arianespace to carry out its initial launches, using the workhorse Russian Soyuz rocket which Arianespace markets to fill the gap between its heavy-lifting Ariane 5 and lighter Vega rockets. The agreement between OneWeb and Arianespace includes launches from three different sites – the Centre Spatial Guyanais in Kourou, French Guiana, the Baikonur Cosmodrome in Kazakhstan, and the Vostochny Cosmodrome in Russia’s far east.

Launches from Baikonur or Vostochny will be subcontracted to Starsem. This partnership is between Arianespace and Roscosmos. Thursday’s launch was the 11th that Arianespace and Starsem have performed for OneWeb and this was the sixth from the Vostochny Cosmodrome. Four of the launches were from Baikonur, and one was from Kourou.

With 36 spacecraft aboard, the total payload mass for Thursday’s launch was 5,797 kg, which includes the satellites themselves as well as their mounting and deployment mechanisms. Soyuz is using a Fregat upper stage to deploy the OneWeb spacecraft into an orbit about 450 kilometers above the Earth, with the satellites using their electric propulsion systems to raise themselves into their operational orbits.

While Soyuz was the preferred launcher for OneWeb’s first missions, the company has signed a letter with the Indian Space Research Organisation’s commercial arm to allow future satellites to be placed aboard its PSLV and the GSLV Mk.III rockets. Although the agreement is not binding, it does allow OneWeb to launch satellites with ISRO. However, it could open the door for India missions to start as soon as next year.

OneWeb has previously explored other providers by signing launch contracts with Blue Origin and Virgin Orbit to enable future missions on their New Glenn rockets. The majority of Virgin’s contracts have been cancelled since then, leading to a legal dispute between both companies. OneWeb also signed a contract with Arianespace for its satellites to be flown on the maiden flight Ariane 6 rocket. However, OneWeb was forced to cancel the deal after it reviewed its deployment plans as OneWeb prepared to emerge from bankruptcy.

More pictures from the #Vostochny_Cosmodrome: the #Soyuz-2.1b with the #Fregat upper stage & 36 @OneWeb satellites are getting prepared for the upcoming launch! pic.twitter.com/U4mcUtWyQP

— GLAVKOSMOS (@glavkosmosJSC) October 11, 2021

The Soyuz 2.1b/Fregat-M rocket for this mission is a four-stage version of the most powerful form of the Soyuz rocket. Soyuz is descended from a series of rockets that trace their lineage back to Sergei Korolev’s R-7 missile of the 1950s, although the current-generation Soyuz-2 rockets were introduced in 2004.

The Soyuz-2 family includes three versions. The Soyuz 2.1a, a modernized version the previous-generation Soyuz-U has upgraded engines and digital flight control systems. The Soyuz 2.1b offers increased performance through a redesign of the third stage, including a new RD-0124 engine. The Soyuz 2.0v is the third variant. It can carry smaller payloads.

The three stages of the Soyuz 2.1b burn RG-1 kerosene propellant and liquid oxygen. This stage is composed of four boosters that are clustered around its core, or second stage. The second stage has four boosters that are clustered around the core – or second – stage. The Fregat upper and OneWeb satellites are enclosed in the payload fairing located at the nose.

The restartable Fregat upper stage was developed from the propulsion system of the Fobos probes that the Soviet Union sent to the Martian moon Phobos in the late 1980s and is frequently used as an upper stage on Soyuz to enable the delivery of satellites into higher, more precise or more complex orbits than would be possible with just the Soyuz vehicle itself.

Fregat burns hypergolic unsymmetrical dimethylhydrazine and dinitrogen tetroxide and can make up to 20 burns in the course of a single mission.

The Soyuz for the OneWeb 11 mission is rolled to the launch pad. (Credit: Roscosmos)

Thursday’s launch used a Soyuz rocket with serial number X15000-009 on a flight designated ST36 by Arianespace and Starsem. The mission will last three hours 51 minutes 40 seconds from liftoff until the final satellite separates.

The flight began from the Vostochny Cosmodrome, Russia’s newest launch site having supported its first launch in April 2016. It is located in Russia’s eastern Amur region. It was constructed on the former Svobodny missile site, which hosted a few orbital launches using the solid-fueled Start rocket.

Vostochny currently has launch facilities for Soyuz rockets, with an Angara launch complex under construction. Pad 1S is the Soyuz complex in Vostochny.

Soyuz was launched to the launch pad Monday, in preparation for the OneWeb mission. The final countdown started nine hours before liftoff. System checkouts were completed on the rocket and ground infrastructure. Fueling began four and a quarter hours prior to launch.

For Soyuz, the final startup sequence saw the first and second stage engines ignite at the T-16 second mark. Each of the four first-stage boosters is powered by a single RD-107A engine while the second stage is powered by an RD-108A that incorporates four vernier nozzles for control of the rocket’s attitude.

Once all combustion chambers have been confirmed as clean, a signal was sent that the engines should be revved to full thrust at T-4 seconds. The rocket will then take off shortly after.

For the first 117 seconds of the flight, the first and second stage engines fired together to propel Soyuz through the dense lower regions of Earth’s atmosphere. After the first stage had consumed its propellant, it shut off and separated. The four boosters were pushed out of the second stage by releasing residual oxygen from their nostrils. The “cross of Korolev”, named after the rocket’s chief designer, can be seen when the boosters are released from the second stage still burning.

Soyuz and OneWeb 11 stand on the launch pad. (Credit: Roscosmos)

Once the rocket crosses out of the aerodynamically sensitive portion of the flight, the payload fairing is no longer needed and separated at about T+3 minutes 35 seconds. The second stage continued to fire until T+4 minutes 46 seconds when the next stage separation event took place.

For the second-third stage separation, Soyuz uses a “hot fire” approach, where the third stage’s RD-0124 engine ignites while the second stage is still burning. Hot staging ensures the rocket is under constant forward acceleration, so that propellants in third stage tanks can remain stable for ignition. Between the second and third stages, there is a lattice interstage that allows exhaust gases to escape during the time between ignition of the third stage and separation.

A few seconds after the second stage separated, the third stage’s aft skirt was also removed. It split into three sections, and fell away from the vehicle. After burning for approximately four and a quarter minutes, the third stage was deployed Fregat just a few seconds later. The first burn of Fregat’s upper stage’s S5. 92 engine began at T+9 minutes 22 seconds and lasted for about five minutes. Fregat started firing again just under an hour later to circle its orbit and set up for the OneWeb satellite deployment.

The satellites separated in nine groups of four, with a gap of just over 19 minutes between each separation event. The first four satellites separated one hour and 18 minutes after launch, with the final four separating at the three-hour 51-minute 40-second mark. After deploying its payloads Fregat will perform a short engine burn to deorbit the satellite.

Thursday’s launch will be the final OneWeb mission for the year. This ends a string of seven launches in the past six and a quarter months. The next OneWeb mission had been expected in late December but has slipped to 2022.

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